Protective device.



E. 0. SCHWEITZER & N. J. CONRAD.

. PROTECTIVE DEVICE.

APPLICATION rILED APR.12, 1910.

Patented NOV.v 14, 1911.

"UNITED STATES riniciativa? OFFICE. 'I

. EDMUND O. SCHWEITZER NICHOLAS J. CONRAD, E CHICAGO, ILLINOIS.

PROTECTIVE DEVICE.

Specification of Letters raient.

Patented Ndv. 14, 1911.

To all whom t may concern:

Be it known that we, EDMUND O. SCHWEIT- 2ER and NICHOLAS J. CONRAD, citizens ofthe United States, residing at Chicago, in the county )of Cook and State of Illinois, have invented a certain new anduseful Improvement 'in Protective Devices, of which the following is a' f ull, clear, conciseand exact description, reference being had to the accompanying drawings, forming a part of this specification.

Our invention relates to protective devices" and more particularly to high potential protective devices, and in its preferred-- form consists of a fusible element under tension which is designed to open the circuit we mean, circuits of some thirty-five hunelty Aand advantage.

`dred volts or over. In our application Serial #550,219, filed March 18th, 1910 we set forth a fuse which can be used in 'this connection, which, fuse is more or less under tension depending upon the pull exerted by a coiled element, but which coiled ele-I ment or spring has its pull increased by the increased current on short circuit or overload due to the attraction between the convolutions of the element. this present application we show other features of nov- These features contemplate among others the provision of an in'closing elementkx for a portion of, or the whole fuse, which element vhas poor heat y radiating qualities, and serves as an initial barrier to the arc.

We further contemplate the construction of a spring of sucha character that its resilience will not be impaired on short cir cuits and this is of great importance when it is.' borne in mind that some of the tests .show a current rise of hundreds of amperes on short circuit, even though the-normal l current of the circuit may be three eighths or three tenths of an ampere. In some tests which we have made, we have found that if the regulatingv s ring were not heavy enough, the short circuit would cause the spring to contract and open theivfuse and would heat the spring sutliciently to fuse and to weld convolutions of the spring to,

gether.

tetrachlorid or a similar substance of high acter it is ordinarily not necessary to pro-y vide a permanent vent andthe absence of the vent, of course, prevents atmos heric influence on the inclosed elements. he structure is such however, that a portion thereof may consist of a plug or other openable device,by virtue of which the devicefmay be opened or ruptured in a portion whereof little or no damage will result, should the force of the breaking fuse and a consequent explosion be sufficient to cause disruption.

. IVe will explain our invention more in detail by reference to Ythe accompanying drawing, illustrating the preferred embodiment thereof in which:

Figure 1 is a sectional view of our improved device, and Fig.`2 is a modification- `Referring now particularly to the drawing, we show a glass tube 1 having. an aper- Iture closing cartridge or'similar element 2 which closes the glass tube at that end and which is of such character that it lcan be readily accommodated for mount-ing. `'Ihe cartridge 2 carries a spring 3 soldered or` otherw-ise suitably fastened thereto, which spring is preferably under tension when r holding under similar tension a fuse 4. The fuse'is connected to lthe spring by the` linkf which engages the hook 6, preferably inteend of the fuse is 'fastenedto or carriedv by a post 7 fastened to` a4 plug 8 y carried at the opposite end of the glassv tube 1.

- Similar to the construction described-in our rst aforesaid co-pendng application, the increaseof current in the/convolutions of the spring causes an attraction between said convolutions and this, simultaneously with the heating of the fuse due to increased current, causes a rupture of the fusigrally fastenedfwith the spring. The other llO ' fuse.

ble element. This causes a break between the terminals of the circuit, whichis not only equal to the distance that the spring has been distended but also in addition the length of the fusible element, and in somle cases the length of the link 5, as that falls to the bottom being carried only by the hook 6.

lt will be seen that a very large gap is provided when the fuse is ruptured or blown. Tf the force of the explosion is suf cient, the plug gives way before the other parts and this will not cause any damage,I the parts being mounted in a switchboard for such a contingency. Further our invention contemplates the provision of the spring 3, in such form that a violent short circuit will not heat the spring sufiiciently to deprive it entirely of its resilience.

lVe further make the actionof this protective device posit-ive by covering the fuse in whole orin part by an element of material which is a poor conductor of heat. lVe have found that cork has given good results under the circumstances, and we show such an element made of cork 9 partly inclosing the This cork forms a good initial barrier to the arc. We also find that a suitable material of high dielectric strength sur-- rounding or partly surrounding those parts where the gap is to occur upon rupture of the fuse'is of great advantage. This material may be liquid or Huid or in such a finely divided form that it readily fills in spaces vice. We ind that we get good results `from different characters of structuresby keeping the whole tube.full of liquid or the whole fuse-submerged, or by the liquid illing the device only up to the top of the cork, or even by having the liquid level below the fusible element, when said element is in its onormal condition.

I When the device is used so that the spring 1s at lts lower end so that the liquid also y incloses the spring, the said liquid tends to having an insulating casing, .afuse within the casing, an envelop for said fuse substantially occupying all the available crosssectional space across a portion of said casing, and means to maintain said fusel under tension.

2. A device of the character described having an insulating casing, a fuse within the casing, an envelop for said fuse substantially occupying all the available crosssec tional space across a portion of said casing, said envelop having a hole for said fuse slightly larger than said fuse, and means to maintain said fuse under tension.

3. A device of the character described having an insulating casing, a fuse therein, and a diaphragm through which said fuse passes of inert material which will not combine with the products of combustion upon operation of the fuse.

4. A device of the character described having an insulating casing,a fuse therein, and'a diaphragm through which said fuse passes of inert material which will not combine with thezproducts of combustion upon operation of the fuse, said diaphragm hav- `ing a hole for said fuse only slightly larger than said fuse and which diaphragm serves as a barrier to the formation of an arc upon operation of thefuse.

5. In a device of the class described in combination, a case forming a chamber, a fuse mounted in said chamber, and a solid arc intercepting member inclosed in said chamber, through which the fuse is threaded, said member being supported on said fuse and occupying in excess of fty per cent. of the cross section of said chamber.

6. A device of the class specified having a fuse, a device located between the fuse terminals and adapted to serve as an intercepting device for the fuse arc, a bath of liquid arc extinguishing material arrangedto iow between the fuse terminals upon the operation of the fuse, and means for lengthening the fuse gap when the fuse operates.

7. A device of the class specified having a fuse, a spring acting upon the same, an envelop supported on and closely inclosing said fuse for intercepting the fuse arc, and a liquid bath submerging said fuse and envelop also for use in extinguishing the fuse arc.

8. A device of the class specified having a fuse, a spring acting upon the same, an envelop supported on and closely inclosing said fuse for intercepting the fuse arc, and a liquid bathimmersing the fuse and envelop.

9. A device of the class described having a fuse in a fuse chamber, and also having a solid envelop confining a portion of said fuse and a bath of arc extinguishing liquid submerging said fuse and envelop.

10. A device of the class specified, having a fuse and means for inclosing a portion of the fuse in an envelop of solid material, and

another portion of the u'se in a liquid bath.

11. A device of the class specied having a fuse in a fuse chamber, and also having a soli-d envelop confining a portion of said fuse, and a bath of arc extinguishing liquid filling the remainder of the fuse chamber.

12. A device of the class specified comprising a tubular casing, terminals at the ends of said casing, a fuse within the fuse chamber formed by said casing, a spiral spring acting upon said fuse, a piece of cork inclosing a portion of the fuse, and an arc extinguishing liquid filling the remainder of the fuse chamber.

13. A device ofthe class specified having a fuse and abarrier of solid material through which the fuse is extended, the aperture for the fuse in saidy barrier being of. substantially the same size as the fuse, a bath of arcl extinguishing liquid, in which the fuse and barrier are immersed, and a springmain- .taining the 'inse under tension.

14. A device of the .class specified having a casing providing a fuse chamber, a fuse therein, a spring .normally maintaining said fuse under tension, a barrier of solid mate.

rial, through which said fuse is extended, the aperture for the fuse in said barrier being of substantially the size of the fuse, and

the barrier being smaller than the interior of whereby when an aperture of substantially the size of the f fuse.

- In witness whereof, we hereunto subscribe our names this fifth day of April A. D., 1910.

EDMUND oi SCHWEITZER. NICHOLAS J. CONRAD.

Witnesses:

MAX W. ZABEL, HAzEL J ONES. 

